Page 298 - Algae

Algae and Men 281

THERAPEUTIC SUPPLEMENTS
Microalgae are a unique source of high-value compounds and systematic screening for therapeutic
substances, particularly from cyanobacteria, has received great attention. Among cyanobacteria
Spirulina sp. has undergone numerous and rigorous toxicological studies that have highlighted
its potential therapeutic applications in the area of immunomodulation, anticancer, antiviral, and
cholesterol reduction effects.
A number of extracts were found to be remarkably active in protecting human lymphoblastoid
T-cells from the cytopathic effects of HIV infection. Active agents consisting of sulfolipids with
different fatty acid esters were isolated from Lyngbya lagerheimii and Phormidium tenue.
Additional cultured cyanobacterial extracts with inhibitory properties were also found in Phormi-
dium cebennse, Oscillatoria raciborskii, Scytonema burmanicum, Calotrix elenkinii, and Anabena
variabilis. A protein called cyanovirin, isolated from an aqueous cellular extract of Nostoc elipso-
sporum prevents the in vitro replication and citopathicity of primate retroviruses.
Cryptophycin 1, an active compound isolated from Nostoc strain GSV224, exerts antiprolifera-
tive and antimitotic activities by binding to the ends of the microtubules, thus blocking the cell
cycle at the metaphase of mitosis. Cryptophycin 1 is the most potent suppressor of microtubule
dynamics yet described. Research has been focused on its potent antitumor activity and a synthetic
analogue, cryptophycin-52, is at present in Phase II clinical trials by Eli Lilly & Co, Inc. (Indiana-
polis, IN). Other studies using water soluble extracts of cyanobacteria have found a novel sulfated
polysaccharide, calcium spirulan to be an antiviral agent. This compound appears to be selectively
inhibiting the penetration of enveloped viruses into host cells, thereby preventing the replication.
The effect was described for many different viruses like herpex simplex, measles, and even
HIV-1.
Among eukaryotic microalgae, a glycoprotein prepared from Chlorella vulgaris culture super-
natant exhibited protective activity against tumor metastasis and chemotherapy-induced immuno-
suppression in mice.
Extracts from several macroalgae may prove to be a source of effective antiviral agents;
although the tests have been either in vitro (in test-tubes or similar) or on animals, with few advan-
cing to trials involving people. A notable exception is Carraguard, a mixture of carrageenans similar
to those extracted from Irish moss. Carraguard has been shown to be effective against
human immunodeficiency virus (HIV) in vitro and against herpes simplex virus in animals.
Testing has advanced to the stage where the international research organization, the Population
Council, is supervising large-scale HIV trials of Carraguard, involving 6000 women over 4 yr.
Extracts from the brown macroalgae, Undaria pinnatifida, have also shown antiviral activity; an
Australian company is involved in several clinical trials, in Australia and the U.S., of such an
extract against HIV and cancer. The Population Council’s trials against HIV involve the vaginal
application of a gel containing carrageenan. Because antiviral substances in macroalgae are com-
posed of very large molecules, it was thought they would not be absorbed by eating macroalgae.
However, it has been found in one survey that the rate of HIV infection in macroalgae-eating
communities can be markedly lower than it is elsewhere. This has led to some small-scale trials
in which people infected with HIV ate powdered Undaria, with a resulting decrease of 25% in
the viral load.
Fucoxanthin, a carotenoid commonly distributed in brown algae, such as U. pinnatifida,
Scytosiphon lomentaria, Petalonia binghamiae, and Laminaria religiosa, is a potent drug candidate
and can be utilized as an excellent supplement like astaxanthin, because it acts as an antioxidant
and inhibits GOTO cells of neuroblastoma and colon cancer cells. Recently, the apoptosis
activity against HL-60 (human leukema) and Caco-2 (cancer colon) cells has been reported for
fucoxanthin.
Among the microalgal high-value compounds there are carotenoids such as b-carotene, astax-
anthin, PUFA such as DHA and EPA, and polysaccharides such as b-glucan. Carotenoids by their